Previous research in this and in other laboratories indicates that certain elicited reflexes can be modified (either augmented or inhibited) if the reflex eliciting event is accompanied by a mild exteroceptive stimulus at an appropriate lead interval. For example, either a weak tone or a dim flash of light can inhibit the startle reaction to a loud sound in th rat and it can inhibit the reflexive eyeblink that is elicited by a tap to the forehead in humans. The present sequence of investigations is designed to document the earliest manifestations of reflex modification in human infants and to compare them to those of adults. In addition to examining reflex modification effects in healthy day old full-term infants, the work will study these effects in infants who are at risk for deficits in sensorineural processing. Subject populations will include infants who are premature or of low birth weight, or suffering from perinatal aphyxia, as well as infants exposed to aminoglycoside therapy and those at risk for SIDS.